Vibrating gyro element, support structure of vibrating gyro element, and gyro sensor
A vibrating gyro element includes in the same plane a base portion; a pair of vibrating arms for detection extended out of the base portion on both sides in a straight line shape; a pair of connecting arms extended-out from the base portion onto both sides in directions perpendicular to the vibrating arms for detection; a pair of vibrating arms for driving each extended-out from the tip portion of each of the connecting arms to both sides perpendicularly to this tip portion; two pairs of beams extended out of the base portion along the respective arms for detection; and a pair of support portions to which the respective beams extended out in the same direction are connected; wherein the support portion is arranged outside the vibrating arm for detection between the vibrating arms for driving in the extending-out direction of each of the vibrating arms for detection.
1. Technical Field
The present invention relates to a vibrating gyro element, a support structure of the vibrating gyro element, and a gyro sensor used in the detection of an angular velocity.
2. Related Art
In recent years, the gyro sensor having the vibrating gyro element stored in a container is largely used as a manual moving correction of an image pickup device, posture control of a mobile navigation system of a vehicle, etc. using a GPS satellite signal.
For example, a so-called double T-type vibrating gyro element is known as the vibrating gyro element in JP-A-2001-12955 and FIG. 1. In this double T-type vibrating gyro element, a driving vibrating system of about the T-type is arranged in left-right symmetry with respect to a central detecting vibrating system.
In these gyro sensors, there is a request of compactness to improve portability and the degree of freedom of a device design. It is necessary to make the gyro element compact so as to make this gyro sensor compact. With respect to support of the gyro element, a central base portion (gravity center portion) of the gyro element is normally adhered and supported in a substrate, etc. However, as the gyro element is made compact, a problem exists in that a support area with respect to the substrate is also reduced and no strength can be secured when a vibration or an impact is applied. Therefore, for example, as shown in JP-A-2001-12955 (FIG. 4), a structure for extending a support frame out of the base portion and respectively supporting the base portion and the support frame is proposed.
However, in this former gyro element, a detecting vibration is suppressed by supporting the base portion, and detecting sensitivity of the angular velocity is reduced. Further, since the support frame is arranged outside the driving vibrating system and the detecting vibrating system of the gyro element, there is a limit in the compact formation of the gyro element.
SUMMARYAn advantage of some aspects of the invention is to provide a vibrating gyro element, a support structure of the vibrating gyro element, and a gyro sensor for maintaining the detecting sensitivity of the angular velocity of the vibrating gyro element, and securing the support strength and able to be made compact.
To achieve the above advantage, a vibrating gyro element of the invention comprises in the same plane:
a base portion;
a pair of vibrating arms for detection extended out of the base portion on both sides in a straight line shape;
a pair of connecting arms extended-out from the base portion onto both sides in directions perpendicular to the vibrating arms for detection;
a pair of vibrating arms for driving each extended-out from the tip portion of each of the connecting arms to both sides perpendicularly to this tip portion;
two pairs of beams extended out of the base portion along the respective arms for detection; and
a pair of support portions to which the respective beams extended out in the same direction are connected;
wherein the support portion is arranged outside the vibrating arm for detection between the vibrating arms for driving in the extending-out direction of each of the vibrating arms for detection.
In accordance with this construction, the area of the support portion can be largely secured by forming the beam extended out of the base portion of the vibrating gyro element, and the support portion for connecting this beam. Thus, support strength can be improved by adhering and supporting this support portion while maintaining the detecting sensitivity of the angular velocity. Further, the vibrating gyro element can be made compact by arranging the support portion outside the vibrating arm for detection between the vibrating arms for driving in the extending-out direction of the vibrating arm for detection.
The vibrating gyro element of the invention is also characterized in that the length of the vibrating arm for detection is formed so as to be shorter than the length of the vibrating arm for driving.
In accordance with such a construction, the area of the support portion can be increased, and the support strength of the vibrating gyro element can be improved.
The vibrating gyro element of the invention is also characterized in that the pair of support portions are arranged in positions of rotation symmetry with respect to the center of gravity of the vibrating gyro element.
In accordance with this construction, the balance of the vibrating gyro element can be secured, and a stable posture can be held.
A support structure of a vibrating gyro element in the invention comprises:
the above vibrating gyro element;
a support base for placing the vibrating gyro element thereon; and
a fixing member for fixing the support portion of the vibrating gyro element and the support base.
In accordance with this construction, since the area of the support portion can be largely formed, the support portion is supported by the fixing member without supporting the base portion of the vibrating gyro element. Thus, the support portion can be reliably supported while maintaining the detecting sensitivity of the angular velocity.
The support structure of the vibrating gyro element in the invention is also characterized in that the fixing member is constructed by a material having elasticity.
In accordance with this construction, since the fixing member has elasticity, a vibration or an impact from the exterior is relaxed, and the driving vibration and the detecting vibration of the vibrating gyro element can be stably held. With respect to a micro vibration coming to be leaked to the support portion, the fixing member functions as a buffer material, and an influence onto the driving vibration and the detecting vibration can be reduced.
A gyro sensor of the invention comprises:
the above vibrating gyro element;
a support base for placing the vibrating gyro element thereon;
a fixing member for fixing the support portion of the vibrating gyro element and the support base;
a driving circuit for operating and vibrating the vibrating gyro element; and
a detecting circuit for detecting a detecting vibration caused in the vibrating gyro element when an angular velocity is applied to the vibrating gyro element.
In accordance with this construction, support strength is improved by adhering and supporting the support portion of the vibrating gyro element while maintaining the detecting sensitivity of the angular velocity. Further, it is possible to provide a gyro sensor which mounts the vibrating gyro element made compact and is made compact.
BRIEF DESCRIPTION OF THE DRAWINGSThe invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
Embodiment modes for embodying the invention will next be explained in accordance with the drawings.
Embodiment Mode
The vibrating gyro element 1 is formed from crystal as a piezoelectric material. The crystal has an X-axis called an electric axis, a Y-axis called a mechanical axis, and a Z-axis called an optical axis. The vibrating gyro element 1 has a predetermined thickness in the Z-axis direction, and is formed within an XY plane.
The vibrating gyro element 1 has a pair of vibrating arms 11a, 11b for detection extended out of a base portion 10 in a straight line shape on both the upper and lower sides within
Further, unillustrated detecting electrodes are formed on the surfaces of the vibrating arms 11a, 11b for detection. Unillustrated driving electrodes are formed on the surfaces of the vibrating arms 14a, 14b, 15a, 15b for driving. Thus, a detecting vibrating system for detecting an angular velocity is constructed by the vibrating arms 11a, 11b for detection. A driving vibrating system for operating the vibrating gyro element is constructed by the connecting arms 13a, 13b and the vibrating arms 14a, 14b, 15a, 15b for driving.
Weight portions 12a, 12b are formed in the respective tip portions of the vibrating arms 11a, 11b for detection, and weight portions 16a, 16b, 17a, 17b are formed in the respective tip portions of the vibrating arms 14a, 14b, 15a, 15b for driving so that detecting sensitivity of the angular velocity is improved. Here, the vibrating arms 11a, 11b for detection are terms respectively including the weight portions 12a, 12b, and the vibrating arms 14a, 14b, 15a, 15b for driving are terms respectively including the weight portions 16a, 16b, 17a, 17b.
Further, the vibrating arms 11a, 11b for detection are formed so as to be shorter in length than the vibrating arms 14a, 14b, 15a, 15b for driving.
Further, a pair of beams 20a, 20b of an L-shape are formed so as to be extended out of the base portion 10 on both the left and right sides within
This pair of support portions 22a, 22b are arranged outside the vibrating arms 11a, 11b for detection between the vibrating arms 14a, 14b, 15a, 15b for driving in the extending-out direction of each of the vibrating arms 11a, 11b for detection. Further, this pair of support portions 22a, 22b are arranged in positions of rotation symmetry with respect to the gravity center G of the vibrating gyro element 1.
The operation of the vibrating gyro element 1 will next be explained.
In
When the angular velocity ω around the Z-axis is applied to the vibrating gyro element 1 in a state in which this driving vibration is performed, the vibration as shown in
At this time, a peripheral portion of the base portion 10 is vibrated in the circumferential direction with respect to the gravity center G in the direction of an arrow D. This is because the detecting vibration becomes a balance vibration including the base portion 10 as well as the balance vibration of the driving vibrating system and the vibrating arms 11a, 11b for detection. The vibrating amplitude of the peripheral portion of the base portion 10 shown by this arrow D is very small in comparison with the vibrating amplitude of the driving vibrating system shown by the arrow B, or the vibrating amplitudes of the vibrating arms 11a, 11b for detection shown by the arrow C. However, for example, when the base portion 10 is adhered and fixed, the vibration of the peripheral portion of the base portion 10 is suppressed by this fixation, and the detecting vibration is also suppressed. Thus, the detecting sensitivity of the angular velocity is reduced by supporting the base portion 10.
The support structure of the vibrating gyro element and the gyro sensor will next be explained by using
The gyro sensor 80 has the vibrating gyro element 1, an IC 84, a storing container 81 and a cover body 86. The IC 84 is arranged on the bottom face of the storing container 81 formed by ceramic, etc., and is electrically connected to unillustrated wiring formed in the storing container 81 by a wire 85 of Au, etc. The IC 84 includes a driving circuit for operating and vibrating the vibrating gyro element 1, and a detecting circuit for detecting the detecting vibration caused in the vibrating gyro element 1 when the angular velocity is applied. In the vibrating gyro element 1, a support base 82 formed in the storing container 81, and support portions 22a, 22b of the vibrating gyro element 1 are adhered and supported through a fixing member 83 such as an electrically conductive adhesive, etc. Further, unillustrated wiring is formed on the surface of the support base 82, and the electrode of the vibrating gyro element 1 and the wiring are conducted through the fixing member 83. This fixing member 83 is desirably constructed by a material having elasticity. An electrically conductive adhesive, etc. having silicon as a base material are known as the fixing member 83 having elasticity. The interior of the storing container 81 is held in the atmosphere of a vacuum in the upper portion of the storing container 81, and is sealed by the cover body 86.
As mentioned above, in the vibrating gyro element 1 and the support structure of the vibrating gyro element 1 in this embodiment mode, the areas of the support portions 22a, 22b can be largely secured by forming the support portions 22a, 22b for connecting the beams 20a, 20b, 21a, 21b extended out of the base portion 10. Thus, support strength can be improved.
Further, since the beams 20a, 20b, 21a, 21b extended out of the base portion 10 are formed by crystal, elasticity is provided and no vibration of the peripheral portion of the base portion 10 is suppressed, and no detecting sensitivity of the angular velocity is reduced.
Further, the vibrating gyro element 1 can be made compact by arranging the support portions 22a, 22b outside the vibrating arms 11a, 11b for detection between the vibrating arms 14a, 14b, 15a, 15b for driving in the extending-out directions of the vibrating arms 11a, 11b for detection.
Further, since the pair of support portions 22a, 22b are arranged in positions of rotation symmetry with respect to the gravity center G of the vibrating gyro element 1, the balance of the vibrating gyro element 1 can be secured and a stable posture can be held and preferable characteristics can be obtained.
Further, in the support structure of the vibrating gyro element 1, the fixing member 83 is constructed by a material having elasticity. Therefore, a vibration and an impact from the exterior can be relaxed, and the driving vibration and the detecting vibration can be stably held. With respect to a micro vibration coming to be leaked to the support portions 22a, 22b, the fixing member 83 functions as a buffer material and an influence onto the driving vibration and the detecting vibration can be reduced.
Further, the gyro sensor 80 mounting the vibrating gyro element 1 supported by the above support structure can be made compact while maintaining the detecting sensitivity of the angular velocity.
Modified Examples of Vibrating Gyro Element
FIGS. 5 to 9 are schematic plan views showing modified examples of the vibrating gyro element. These modified examples have features in the shapes of the beam and the support portion shown in
In
This pair of beams 31a, 31b are arranged outside the vibrating arms 11a, 11b for detection between the vibrating arms 14a, 14b, 15a, 15b for driving in the extending-out directions of the respective vibrating arms 11a, 11b for detection.
The vibrating gyro element 2 has a support structure similar to that of the above embodiment mode, and the support portions 32a, 32b are adhered and supported in a support base by a fixing member such as an electrically conductive adhesive, etc.
Next, in
This pair of support portions 41a, 41b are arranged outside the vibrating arms 11a, 11b for detection between the vibrating arms 14a, 14b, 15a, 15b for driving in the extending-out directions of the respective vibrating arms 11a, 11b for detection.
The vibrating gyro element 3 has a support structure similar to that of the above embodiment mode, and the support portions 42a, 42b are adhered and supported in a support base by a fixing member such as an electrically conductive adhesive, etc.
In
This pair of support portions 51a, 51b are arranged outside the vibrating arms 11a, 11b for detection between the vibrating arms 14a, 14b, 15a, 15b for driving in the extending-out directions of the respective vibrating arms 11a, 11b for detection.
The vibrating gyro element 4 has a support structure similar to that of the above embodiment mode, and the support portions 52a, 52b are adhered and supported in a support base by a fixing member such as an electrically conductive adhesive, etc.
Next, in
This pair of support portions 61a, 61b are arranged outside the vibrating arms 11a, 11b for detection between the vibrating arms 14a, 14b, 15a, 15b for driving in the extending-out directions of the respective vibrating arms 11a, 11b for detection.
The vibrating gyro element 5 has a support structure similar to that of the above embodiment mode, and the support portions 62a, 62b are adhered and supported in a support base by a fixing member such as an electrically conductive adhesive, etc.
Beams 70a, 70b, 71a, 71b of an L-shape are arranged in a vibrating gyro element 6 so as to be extended out of the corner portions of four places of the base portion 10 on both the left and right sides within
This pair of support portions 71a, 71b are arranged outside the vibrating arms 11a, 11b for detection between the vibrating arms 14a, 14b, 15a, 15b for driving in the extending-out directions of the respective vibrating arms 11a, 11b for detection.
The vibrating gyro element 6 has a support structure similar to that of the above embodiment mode, and the support portions 72a, 72b are adhered and supported in a support base by a fixing member such as an electrically conductive adhesive, etc.
Thus, although the crystal as a material of the vibrating gyro element has a proper elastic property, the elastic property of the beam can be adjusted by suitably changing the length and shape of the beam extended out of the base portion 10. Thus, it is restrained to transmit the vibration of the base portion 10 to the support portion, and stable driving vibration and detecting vibration can be obtained.
Actions similar to those explained in this embodiment mode are also provided and similar effects can be also obtained in the above modified examples of the vibrating gyro element.
The vibrating gyro element of this embodiment mode can be integrally formed by etching processing using a photolithography technique, and many vibrating gyro elements can be formed from one crystal wafer.
Lithium tantalate (LiTaO3) or lithium niobate (LiNbO5), etc. as another piezoelectric material may be also utilized as the material of the vibrating gyro element. Further, the vibrating gyro element can be also embodied by using a perpetuating elastic material represented by an elinvar material as well as the piezoelectric material.
The entire disclosure of Japanese Patent Application No. 2005-012418, filed Jan. 20, 2005 is expressly incorporated by reference herein.
Claims
1. A vibrating gyro element comprising in the same plane:
- a base portion;
- a pair of vibrating arms for detection extended out of the base portion on both sides in a straight line shape;
- a pair of connecting arms extended-out from the base portion onto both sides in directions perpendicular to the vibrating arms for detection;
- a pair of vibrating arms for driving each extended-out from the tip portion of each of the connecting arms to both sides perpendicularly to this tip portion;
- two pairs of beams extended out of the base portion along the respective arms for detection; and
- a pair of support portions to which the respective beams extended out in the same direction are connected;
- wherein the support portion is arranged outside the vibrating arm for detection between the vibrating arms for driving in the extending-out direction of each of the vibrating arms for detection.
2. The vibrating gyro element according to claim 1, wherein the length of the vibrating arm for detection is formed so as to be shorter than the length of the vibrating arm for driving.
3. The vibrating gyro element according to claim 1, wherein the pair of support portions are arranged in positions of rotation symmetry with respect to the center of gravity of the vibrating gyro element.
4. A support structure of a vibrating gyro element comprising:
- the vibrating gyro element according to claim 1;
- a support base for placing the vibrating gyro element thereon; and
- a fixing member for fixing the support portion of the vibrating gyro element and the support base.
5. The support structure of the vibrating gyro element according to claim 4, wherein the fixing member is constructed by a material having elasticity.
6. A gyro sensor comprising:
- the vibrating gyro element according to claim 1;
- a support base for placing the vibrating gyro element thereon;
- a fixing member for fixing the support portion of the vibrating gyro element and the support base;
- a driving circuit for operating and vibrating the vibrating gyro element; and
- a detecting circuit for detecting a detecting vibration caused in the vibrating gyro element when an angular velocity is applied to the vibrating gyro element.
Type: Application
Filed: Jan 10, 2006
Publication Date: May 25, 2006
Patent Grant number: 7412885
Inventor: Seiichiro Ogura (Nagano-ken)
Application Number: 11/329,691
International Classification: G01P 15/08 (20060101);